C7 guitar chord
The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
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About C7 — drop 3 voicings
C7 is C, E, G and Bb — C with the flat seventh added on top.
It sounds restless and pointed at something. The third and the flat seventh are a tritone apart and each moves by a semitone into the next chord; that is the engine of a cadence, and the whole vocabulary of the blues.
C7 notes and formula
| C | E | G | Bb |
|---|---|---|---|
| 1 | 3 | 5 | ♭7 |
Dominant — it points a fifth down.
Also written Cdom7 or C dominant 7. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C7
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
C7 has 10 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 13th — every inversion the chord has: C in the bass, E in the bass, G in the bass and Bb in the bass. The one to learn first is the G shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x32310 — no barre and 1 open string. 1 of the 7 shapes here sits in open position. 4 of the 7 need a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x32310 | open position | C, root position | E | 1 open string |
| x35353 | 3rd fret | C, root position | G | barred |
| xx5556 | 5th fret | G, 2nd inversion | Bb | barred |
| 875556 | 5th fret | C, root position | Bb | barred |
| 8-10-8-9-8-8 | 8th fret | C, root position | C | barred |
| x-x-10-12-11-12 | 10th fret | C, root position | E | all fretted |
| x-15-14-15-13-x | 13th fret | C, root position | C | all fretted |
The same notes rebuilt from scratch give 5 shell, 15 drop 2 and 6 open string voicings, each on its own page.
Tensions. A shell of C7, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Db), the 9 (D), the #9 (D#), the #11 (F#), the b13 (Ab) and the 13 (A).
How to use C7
C7 is the V of F, and that is where it goes if it goes anywhere: the third and the flat seventh are a tritone apart, and both resolve by a semitone into F.
Voice by voice, C7 → F. 2 voices move by a semitone, and one note is common to both chords.
| In C7 | Moves | In F |
|---|---|---|
| C, the root | stays where it is | C, the fifth |
| E, the major third | rises a semitone | F, the root |
| G, the fifth | falls a whole tone | F, the root |
| Bb, the flat seventh | falls a semitone | A, the major third |
In which keys. Every note of C7 belongs to D minor (the ♭VII) and F major (the V, the dominant).
What to play over C7
Every note of C7 is in C mixolydian, C lydian dominant and C half-whole diminished.
Chords near C7
Change one note of C7 and you have C (drop the flat seventh), Cmaj7 (the flat seventh becomes a major seventh), Cm7 (the major third becomes a minor third), Cadd9 (the flat seventh becomes a ninth), C6 (the flat seventh becomes a sixth) or C7sus4 (the major third becomes a fourth).
C7 is a dominant chord — root, major third, fifth, minor seventh. Dominant seventh chords on every root.
On C7’s sound and use this page follows Edward Aldwell & Carl Schachter, Harmony and Voice Leading (Schirmer / Cengage, 4th ed., 2011). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.